My best experience of a good working-hours week comes from a school i studied at when a boy. The hours were 11:30AM to 4:30PM; i.e. 5 hours with only a 20/30min break in-between. We slept well, had a good brunch and went to school fresh and energetic. Played outside after school (i.e. exercise), came home at nightfall, did some study (i.e. work), had some entertainment and dinner before hitting the bed.

In today's parlance, this was excellent "work-life balance". If you can, talk to your boss and see whether you can adopt such a work schedule (with slight shifting of the time window as needed).